MALARIA

In this article, we’re going to review Malaria in children

PATHOLOGY

  • Malaria is a disease that is spread by the Anopheles mosquito.
  • This was largely eliminated from the United States in the early 1950s. It used to go all the way up to as far north as Rhode Islands, but now it’s mostly gone.
  • Nonetheless, it is prevalent throughout other countries in the world and is one of the greatest killers of children worldwide especially P. falciparum in Africa.
  • There are more than 100 species of Plasmodium that can infect humans, and it is not necessary to remember all these different species but there are a few that are key to understand because they are somewhat different in terms of how they come on.
  • So, P. vivax is clearly different because the liver dormant stage can relapse up to 2 years after the bite. In other words, a patient can have a period of 2 years when they are relatively asymptomatic before developing symptoms of malaria.
  • Ovale, that relapse can be even 4 years after the bite.
  • falciparum is a major cause of death in sub-Southern Africa, and what’s key to remember is that there is increased susceptibility to this one especially in pregnant women.
  • Likewise, P. malariae has a longer incubation period and is more likely to cause, for example, nephrotic syndrome.
  • So, there are slight differences to these but mostly they’re fairly similar.

LIFECYCLE OF MALARIA

Basically, the Anopheles mosquito bites the person. The Plasmodium then go as sporozoites down into the liver, and we have the liver stage of the disease. This organism replicates in the liver then and ruptures from the liver into the blood stage of the disease in which the organism is infecting serially red blood cells. Lastly, we have the gametocyte stage which is when now the organism can go back into the next mosquito and be shed to someone else.

CLINICAL PRESENTATION

  • So, understanding malaria is important and we should understand the incubation period. Typically, the time between being bitten and developing symptoms is 7 to 30 days. Falciparum is often a little bit shorter.
  • A long incubation period can confuse physicians and immigrants and travellers.

Uncomplicated Malaria

  • Now, the patient develops symptoms of uncomplicated malaria. This basically is an attack, a fever, which will typically last 6 to 10 hours and occur every 2 to 3 days.
  • The stages can be named as the cold stage which will last about 15 to 60 minutes when the patient feels cold. Followed by the hot stage when the patient is overtly febrile between 2 and 6 hours, and then the sweating stage which is 2 to 4 hours after that. This will recur over and over and over again.
  • Also, symptoms may include headaches, nausea, vomiting, body aches, and generalized malaise.

Physical Findings

The physical findings can be including fever and perspiration as we’ve discussed but patients may also have a weakness, they often have hepatosplenomegaly, they may have jaundice from the increased red blood cell breakdown and they may have tachypnea. Children tend to get tachypnea often with fever. It is sort of like an inflammatory response.

Severe Malaria

  • More severely, malaria can present with really large problems.
  • One of those is cerebral malaria, which is overtly dangerous.
  • These patients can have altered mental status and be very, very sick.
  • Patients may develop severe anemia and that anemia can be so low they may require transfusions.
  • They may develop hemoglobinuria, a darkening red-brown color to the urine that is obvious to the patient.
  • In severe cases, they can go into ARDS or acute respiratory distress syndrome
  • They may develop frank DIC or disseminated intravascular coagulation.
  • Keep in mind, patients may just go into distributive shock and have hypotension requiring either fluid resuscitation or dopamine and
  • Patients can go into acute renal failure.

So, the clinical presentation is different a little bit in that P. vivax and P. ovale typically may present with relapses months or years later because of a persistence of the liver stage. So, these 2 ones can happen years after already returning back from an endemic area.

Patients with cerebral malaria are at risk for chronic brain problems and we have to keep an eye out for those and don’t forget that chronic or repeated P. malariae may be associated with nephrotic syndrome.

Diagnosis

So, if we suspect bradycardia in a patient, the obvious thing is we’re gonna get an EKG and that’s really gonna help us make our diagnosis.

There are times, however, when patients come in and out of bradycardia or they’re having some symptoms sometimes but not others, and that’s when we might do something like 24-hour Holter monitoring.

  • 24-hour Holter monitoring is really clever.
  • It’s a machine, a device that the patient carries with him for a day.
  • They have a button they could actuate and press if they have feeling symptoms, and it’s measuring their heart rate continuously and recording that.
  • Then the device is taken to the cardiologist, and the cardiologist can look at the device and see what exactly is going on with the heart at that time.

Management

Let’s look at all the drugs we have available to us for the treatment of malaria.

We have mefloquine, we have atovaquone-proguanil, we have Coartem, we have quinidine, we have quinine, we have chloroquine, and these are all the quinolones. Doxycycline can be used sometimes in combination with a quinine, the same thing with clindamycin, and there is artesunate, which is not licensed for use in the US although it is available through CDC hotline if you are in a situation where you have a resistant organism and you need that drug. And last, primaquine, which is really for relapse prevention because it is directed mostly against the liver form. So, there are lots of drugs available for this disease.

  • Generally, we would like to prophylax people before they travel to an endemic area. I’d just like to take a moment to plug a website from the CDC for travellers internationally outside of the United States. You go to the CDC website, you can plug in the country and it will tell you what you need to watch out for if you’re travelling to that country. It‘s remarkably useful.
  • In many countries, especially in equatorial areas around the world, we would recommend prophylaxis for people who are travelling to that endemic area. Sometimes, certain prophylaxis is required in certain areas but let’s go to the general prophylaxis regimens.
  • The first is Malarone. Malarone is given daily, it’s very well tolerated but we can’t give that for newborns.
  • Another opportunity for daily prophylaxis is doxycycline. We don’t recommend that for children under 8, as you recall that can cause lines in the bones and the teeth.
  • Mefloquine is a convenient and easy one or so as chloroquine because these are used weekly, but they are not for use in resistant areas.
  • Chloroquine is useful, again, weekly administration, you need to start 1 to 2 weeks prior to travelling.

So, if we see a patient who has malaria, we usually are required to call an infectious disease consult to help us understand what is the best regimen for that patient.

The drugs of treatment depend on the location where the parasite was encountered and global resistant patterns.

I should point out that the most important thing here, is that this killer is potentially going to be curbed in the future through vaccine use. So, there is active vaccine research going on. So far, we haven’t had much luck, but we’re all keeping our fingers crossed. So, that’s a quick review of Malaria in Children.